Depending on your source, either yesterday or today is Manhattanhenge, a biannual occurrence where the setting sun aligns with the east-west streets of Manhattan’s main street grid (14th Street and farther north). Manhattan has two such days, generally cited as May 28th and July 12th, with some small yearly variation (there are also two days when the effect can be seen at sunrise: December 5 and January 8).

The term Manhattanhenge was coined in 2002 by Neil deGrasse Tyson, an astrophysicist at the American Museum of Natural History, and is based on an analogous occurrence at Stonehenge, where, on the summer solstice, the sun rises in perfect alignment with several of the stones. On the Manhattanhenge days, the sun fully illuminates every cross street on the grid during the last fifteen minutes of daylight. The sun’s center sets exactly on the street’s center line, with the sun 50% above/below the horizon. The effect can be seen from river to river (and from Queens). The effect is good for a day or so on either side.

Many people question the idea that this effect takes place simultaneously at every crosstown street in the grid, regardless of location. This may be counter intuitive, but it is true. The sun’s distance from the Earth at 93 million miles, in comparison to the length of the city’s grid of only a few miles, means that the sun’s rays are essentially parallel once reaching the earth – the deviation from parallel is too small to make a perceptible difference. Also note that Manhattan is rotated 29 degrees from geographic north. If the island’s grid was perfectly aligned with geographic north, Manhattanhenge would occur on the spring and autumn equinoxes.

Viewing recommendations and photo notes: You still have time to see this effect in the next day or so. Recommended viewing is as far east as possible. However, keep in mind that many streets do not go clear through or have obstructions on the west side, the slight hilliness of the city may limit the view from First Avenue, and the actual horizon cannot be seen due to various buildings on the skyline in New Jersey. Queens or Roosevelt Island would also be good viewing areas. The photos were taken at 34th Street and Park Avenue – there was a fairly good crowd for the event. We dodged traffic, standing in the center of the street between changing lights.